The Urban Centres and Localities/Section of State (UCL/SOS) structure is intended primarily for the dissemination of statistics from the Census of Population and Housing. The structure represents areas of concentrated urban development. It consists of Statistical Areas Level 1 (SA1s) aggregated together to form regions defined according to population density and other criteria.

UCL/SOS does not explicitly define rural Australia; however, in practice, any population not contained in an Urban Centre is considered to be rural. It is important to realise that the Bounded Localities and Rural Remainder areas, commonly combined to define 'rural Australia', contain considerable areas of urban style development, peri-urban development and substantial infrastructure.